Influence of Stress and Defect on Magnetic Properties of Mn3O4 Films Grown on MgAl2O4 (001) by Molecular Beam Epitaxy

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• 作者：Lizhu Ren ; Mei Yang ; Wenqi Zhou ; Shuxiang Wu ; Shuwei Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：243-249
• 全文大小：373K
• ISSN：1932-7455

文摘

Three single-crystal Mn₃O₄ thin films were grown on MgAl₂O₄ (001) substrates by plasma-assisted molecular beam epitaxy (PA-MBE). The films with different thicknesses are found to be compressed in the (001) plane and elongated in the perpendicular direction at different levels via in situ reflection high-energy electron diffraction (RHEED) and ex situ X-ray diffraction. Magnetic measurements indicate that either of the two thicker films owns smaller spontaneous magnetization, larger coercive force, and higher phase transition temperature than the bulk single-crystal Mn₃O₄ material. On the contrary, it is noteworthy that the thinnest film exerts different characteristics with smaller coercive force and lower phase transition temperature than the bulk. The variation of magnetic properties for the films are proposed to be related to the combined effects of the lattice distortion under epitaxial stress, strain relaxation with the generation of defects and dislocations, and surface roughness, which could influence the magnetic anisotropy and the exchange interactions among the manganese ions in the films with different thicknesses on different levels.